[qartik]

BArrayDiscard freed the elements buffer but left the borrow mask allocated. Free both pointers when discarding the array.

The borrow-array lowering was introduced in #2574.

Add a JIT regression test that creates, accesses, and discards an array 100 times while accounting for allocations and frees. The test fails when the mask free is removed. Update the LLVM snapshots.

Closes #3320

Validation

• cargo test -p hugr-llvm extension::collections::borrow_array::test --lib (84 passed, LLVM 21)
• cargo fmt --all -- --check and git diff --check
• Snyk Code scan of borrow_array.rs: no findings

[chatgpt-codex-connector]

Codex Review Summary

This comment shows the latest Codex review activity on this pull request.

Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-11-04T21:01:59.838639Z	f283f3b	New commits
🔒 Security Review	✅ Completed 2026-11-04T21:03:48.805536Z	f283f3b	New commits

ℹ️ About Codex in GitHub

Your team has set up Codex to review pull requests in this repo. Reviews are triggered when you

• Open a pull request for review
• Mark a draft as ready
• Comment "@codex review" or "@codex security review".

Codex reacts with 👀 while any review is running, comments if it has suggestions, and reacts with 👍 once all reviews finish with no findings.

[Copilot]

🟢 Approval recommended

No active review issues are recorded for the borrow-array discard leak fix.

No open issues 🎉

What changed in this PR

Fixes the borrow-array discard leak in hugr-llvm reported in #3320 by releasing both the elements buffer and the borrow mask.

Changes:

• Frees both pointers in emit_barray_discard.
• Adds a JIT regression test that checks allocation accounting across 100 create/access/discard cycles.
• Updates LLVM 21 snapshots to include mask deallocation.

File	Description
hugr-llvm/​src/​extension/​collections/​snapshots/​hugr_llvm__extension__collections__borrow_array__test__emit_get@pre-mem2reg@llvm21.snap	Records mask deallocation before mem2reg for get/discard.
hugr-llvm/​src/​extension/​collections/​snapshots/​hugr_llvm__extension__collections__borrow_array__test__emit_get@llvm21.snap	Records mask deallocation after mem2reg for get/discard.
hugr-llvm/​src/​extension/​collections/​snapshots/​hugr_llvm__extension__collections__borrow_array__test__emit_clone@pre-mem2reg@llvm21.snap	Records both arrays’ mask deallocation before mem2reg.
hugr-llvm/​src/​extension/​collections/​snapshots/​hugr_llvm__extension__collections__borrow_array__test__emit_clone@llvm21.snap	Records both arrays’ mask deallocation after mem2reg.
hugr-llvm/​src/​extension/​collections/​borrow_array.rs	Fixes discard cleanup and adds the allocation-accounting regression test.

_{Review effort: Balanced}

[codecov]

Codecov Report

❌ Patch coverage is 88.88889% with 4 lines in your changes missing coverage. Please review.
✅ Project coverage is 82.10%. Comparing base (ca20348) to head (f283f3b).

Files with missing lines	Patch %	Lines
...ugr-llvm/src/extension/collections/borrow_array.rs	88.88%	1 Missing and 3 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3321      +/-   ##
==========================================
+ Coverage   82.08%   82.10%   +0.01%     
==========================================
  Files         245      245              
  Lines       47579    47612      +33     
  Branches    41144    41177      +33     
==========================================
+ Hits        39056    39090      +34     
+ Misses       6619     6617       -2     
- Partials     1904     1905       +1     

Flag	Coverage Δ
python	89.72% <ø> (ø)
rust	80.90% <88.88%> (+0.01%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[aborgna-q]

LGTM 👍